Since this thread seemed to be going nowhere, let me clarify some points as a ScummVM developer (albeit not one who worked on the SCI engine):

There is no enforced policy and it is up to the developers working on an engine to decide what they want to fix or implement.

That being said we do usually fix bugs that were present in the original games, and SCI is one of the engines where a lot of such bugs were fixed (see here for a list, although that page is not fully up to date and some more bugs have been fixed since it was last updated).

We do also sometimes implement some new features that were not available in the original game, and we try to make those optional. Again it is up to the engine developers to decide whether they want to accept enhancements or not, and SCI is one of the engines where some enhancements were implemented (such as supporting speech and text together in games that did not originally support using both at the same time).

Yes the issue described here is not a bug in ScummVM, but I don't think anybody claimed it was. We could question whether this is a bug in the original game or if it is how the game is supposed to look, but personally I would consider this a bug (see the previous post from OmerMor - I agree with his arguments).

Whether it gets fixed or not depends on the SCI developers, or if somebody else proposes a fix that gets accepted by them. I would consider this a minor issue, with a low priority, and it might not be easy to fix. And as mentioned by OmerMor, I would suggest reporting this issue to our bug tracker (this would increases the chances that it will be seen by SCI developers and will be fixed).

Hi, the problem that you noticed is related to a bug in qfg1 palette. A lot of year ago than scummvm give support to sci, I and Drigo (author of sciamano suite tools that allow to translate sierra games) translated toghether this game. Drigo is an hell of programmer and fixed this bug. The fix is inserted in our italian translation of the game that you could download from the traduzioni sections of our website oldgamesitalia.net
Probably if you make some experiments you could isolate the fix and even scummvm authors could use it to patch scummvm.

Remember:
1)use the italian translation on the quest for glory anthology qfg1vga
2)the translation is for dos and dosbox but i'm sure it works even in scummvm
3)the fix could be in a single file or a couple of file, but i'm sure that is NOT a .msg file because obviously they are texts files. Could be a .scr or a .hep or a graphic file. trials and errors awaits you XD
4)don'r use a savegame, savegame store a lot of data from the previous game inside and so if you load one and try immeditaley to reproduce the bug you'll have it even if it's already fixed! A trick is to exit from the room and enter again so the old data will be removed from memory.

here i've attached a couple of screen thet show the bug fixed by the translation.